The present invention relates to a ground fault circuit interrupter (GFCI) device. More particularly, the invention relates to a ground fault circuit interrupter device that can directly indicate and display the working conditions of the interrupter to indicate whether the power-input terminal connections are correct.
In general, conventional GFCI devices only display whether the plug-in socket is connected with a power source. Generally, these devices have no means to show the user whether the internal of socket is connected correctly. Furthermore, the socket has only one output meansxe2x80x94the plug-in socket; hence the application scope of conventional GFCI devices is narrow.
There are other GFCIs on the market, as shown in FIG. 1. They typically include a cover plate 1 and main body 2 with power-input terminals 5A and 5B, output terminals 5C and 5D (terminals 5B and 5C are at the symmetrical position of 5A and 5D, located on the other side of main body 2, not shown in FIG. 1), and one or more plug-in output sockets 3. Internal to the main body of conventional GFCIs is a current monitoring circuit, set such that when the current difference between the hot and the neutral lines is larger than the pre-determined value, the GFCI will automatically cut off power output. The GFCI is also equipped with a simulated earth leakage test button (TEST) 6 and reset button (RESET) 7. When RESET 7 is pressed on, output socket 3 and output terminals 5C and 5D receive electricity; when TEST 6 is pressed on, the output terminals are off.
The main drawback of these conventional GFCIs is the lack of a means to clearly indicate whether the power output terminals are charged. As the GFCI devices of this type typically have a pair of naked output terminals 5C and 5D, a careless user has the danger of being shocked, perhaps causing injury or death.
The general object of the present invention is to overcome the aforementioned drawbacks of GFCIs in prior art by providing a means to indicate the working conditions of the interrupter, and thus, whether or not its power-input terminals are connected correctly.
A second object of the present invention is simplicity and reliability of design and operations, enabling low cost manufacture and convenience of use.
To achieve these objectives, the present invention adopts the following design plan. The present invention comprises a cover plate and a main body, including two power-input terminals, one or more plug-in sockets, two power-output terminals, a reset button and a simulated earth leakage test button, an internal current monitoring circuit and internal display circuit. The display circuit is comprised of a variable-color display lamp (LED), a current limiting resistor, and a commutation diode. The variable-color display lamp has a two-color display lamp with three legsxe2x80x94one common leg, and two control legs. The two control legs of the variable-color display lamp are connected with a power-input terminal and a power-output terminal respectively. One of the control terminals and the common terminal of the variable-color display lamp (LED) are connected in series with a current-limiting resistor and a commutation diode to form a loop, and connected in parallel to one side of the power input terminals.
The variable-color display lamp in the display circuit of the present invention may be a common anode or a common cathode variable-color display lamp.